Numerous heavy metals, especially transition metals, have been bonded to the surface of various support materials by reaction of a metal compound with the surface hydroxyl groups. In this way it has been possible to obtain supported catalysts useful for widely diverse applications such as polymerization esterification, hydrogenation oxidation, hydroformylation and the like.
Probably the most common method of bonding a metal to a support is by the reaction of the surface hydroxyl with a metal halide compound. For example, U.S. Pat. No. 3,166,543 shows the reaction of carbon blacks, such as channel carbon blacks which have hydroxyl groups on their surface, with a transition metal halide, e.g. titanium tetrachloride, and subsequently heating with a silane compound to obtain a useful olefin polymerization catalyst. U.S. Pat. No. 3,166,542 similarly discloses polymerization catalysts obtained in much the same manner but where the support material is a finely divided inorganic solid such as alumina, titania, zirconia, thoria, magnesia, silicates or aluminates.
Other methods of attachment are also known. For example, hydroformylation catalysts containing units of the formula ##STR1## where Z represents the support and Q is a group containing phosphorus bonded to a transition metal are described in U.S. Pat. No. 3,832,404 and obtained by (i) reacting a transition metal compound with a compound containing silicon and phosphorus e.g. (EtO).sub.3 Si(CH.sub.2).sub.2 PR.sub.2 to form a compound containing transition metal bonded to phosphorus and reacting this latter compound with an inorganic solid containing -- OH groups or (ii) reacting the inorganic solid with the compound containing silicon and phosphorus and then reacting this product wth the transition metal compound. Transition metal amine compounds, such as tetrakisdiethylaminotitanium, tetrakisdimethylaminozirconium and dichlorodibutylaminotitanium, have also been shown in U.S. Pat. No. 3,392,160 to react with hydroxyl-containing finely divided particulate supports and are then activated by further reaction with an organometallic compound. U.S. Pat. No. 3,816,340 shows the preparation of olefin disproportionation catalysts by reacting a substantially inert matrix having a hydroxylic surface with a transition metal complex such as tetrakis (.pi.-allyl) tungsten or molybdenum.
It is also known to react various metal compounds containing one or more alkoxide groups with hydroxy-bearing support materials. U.S. Pat. No. 3,326,877 discloses polymerization catalysts obtained by reacting a finely divided inorganic support with compounds of the formula T(Q).sub.n where T is a Group IVa, Va or VIa metal and Q is an alkoxy or aryloxy radical and then further reacting with an organometallic compound. This process requires that the support and any diluents or carrier gases be essentially anhydrous when the transition metal ester is contactedwith the support. The presence of water prevents the desired chemical reaction and produces an inferior catalyst component or subsequent reaction with the organometallic compound. No more than transition metal atom is present per surface hydroxyl group and very low levels of transition metal are bound to the support. Similarly, U.S. Pat. No. 3,817,931 discloses catalysts suitable for the production of polyesters which are obtained by reacting a hydroxy-bearing support with metal compounds, including germanium, titanium, zirconium and hafnium alkoxides, in addition to metal halides and organometallic compound. Each metal atom is linked to the support by from 1 to n-1 (where n is the valence of the metal) oxygen linkages (--O--) and the concentration of the bound metal is very low.
Still another reference, U.S. Pat. No. 3,622,522, discloses olefin polymerization catalysts containing up to 15 wt. % gallium and/or tin with up to 50 wt. % chromium. These catalysts are obtained by depositing a chromium compound, such as chromium trioxide, and at least one compound selected from the group of gallium and tin alkoxides or aryloxides with a support and then heating at a temperature of at least 1700.degree. F. The metal compounds preferably are deposited on the support from a nonaqueous solvent or dispersant and the heating is carried out in substantially water free (less than 0.1 wt. % water) air or a stream of oxygen-containing gas.
It would be extremely advantageous if highly active supported transition metal catalysts could be prepared from transition metal alkoxides without taking precautions to exclude moisture normally present on the hydroxylic support material or otherwise present in the reaction system from solvents, diluents, air or carrier gases. It would be even more advantageous if the process could be conducted as a single-step reaction and without subsequent calcining at temperatures of 350.degree. C or higher. The process and catalyst would be even more desirable if it were possible to vary the amount of transition metal bound to the support from small amounts up to very high levels. It would be even more advantageous if the catalysts were recoverable directly from the reaction as free-flowing powders by simply filtering, washing and air-drying and if such products exhibited good catalytic activity.